|PAMD(8)||DACS Web Services and CGI||PAMD(8)|
pamd — PAM transaction server
-h ] [
-p ] [
-policy ] [
This program is part of the DACS suite.
The pamd server is required by the local_pam_authenticate authentication module. It acts as a proxy for local_pam_authenticate, calling PAM functions on its behalf. The pamd server may be started from inetd(8) or from the command line, but it must be running for DACS to perform PAM-based authentication.
Each pamd process is involved in an arbitrarily long "conversation" or "transaction" with one or more executions of local_pam_authenticate. For instance, pamd's initial response to local_pam_authenticate might be that it requires an account name; upon receiving the account name from local_pam_authenticate, pamd's response might be that it requires the password for the account; and upon receiving the password, pamd would indicate success or failure, depending on whether an acceptable username/password pair was received. The eventual outcome of a transaction is that authentication succeeds, fails, or could not be completed because an error occurs.
pamd must be run on the host where pam(3) processing is being performed, which is not necessarily the same host where local_pam_authenticate is executed.
pamd will usually be run as root so that it can access the files it needs to perform authentication.
pamd is not a DACS web service and is not protected by DACS.
The protocol between pamd and its client may include sensitive material, such as passwords. If both programs are run on the same host, this is probably not an issue. If there is any possibility of eavesdropping etc. by an attacker, however, communication should be secured through an SSL/TLS wrapper.
pamd should probably not be run on a world-accessible server, since it would offer a way for attackers to try to guess passwords.
The operating system's PAM policy file is consulted - see
The default PAM service name is "
which may be used by PAM to locate the appropriate policy file.
A different policy name can be specified using the
The prompts that passed from PAM to pamd to
(or dacsauth) are simply displayed to the user.
The user must understand what the prompts mean
(e.g., that "
Login:" means to provide a Unix account
pamd can be used by non-DACS applications. The protocol, though simple, is not yet documented other than within the source code. A program called pamd-client is available for testing and debugging pamd; it is built when PAM support is required, but is neither installed nor documented (see the source code for basic instructions).
In addition to the standard dacsoptions, pamd recognizes these command line flags:
Wait for a connection, then service the request.
Mutually exclusive with
Create a new process to service each request.
It implies the
If pamd is running on a host with multiple IP addresses, this specifies the hostname (or IP address) to listen to for incoming requests. If not provided, the PAMD_HOST directive will be consulted; if unavailable, gethostname(3) will be used.
This flag is reserved for future use.
The server assumes it has been started by inetd(8) and therefore does not wait for a connection. It exits after servicing the request. This is the default behaviour and preferred way to configure pamd. This mode of operation assumes that an entry has been added to inetd.conf(5) that looks much like this:
dacs-pamd stream tcp nowait root /usr/local/dacs/sbin/pamd pamd -uj EXAMPLE -inetd
This flag, which implies the
causes the pamd server to exit
after servicing one request (which is useful when debugging).
This is the default behaviour of
This specifies the port number to listen to, overriding any PAMD_PORT directive in effect. It can also be a service name. Any otherwise unassigned port number on the system from 49152 through 65535 (i.e., one in the dynamic and/or private range) ought to be acceptable.
If neither this flag nor a PAMD_PORT directive is provided, the program will try to find the port associated with the dacs-pamd service name in services(5). For example:
dacs-pamd 17000/tcp # DACS pamd
name as the
PAM policy name instead of the default.
The client must supply valid DACS administrative credentials encapsulated within a DACS cookie. This is the default.
Administrative credentials are not required, but if they are provided they must be valid. This should probably be used only when testing or if client identification is not an issue or has been addressed in some other way.
For testing purposes, or to better understand how pamd works, you can run it manually and interact with it using telnet(1), for example, which takes the place of local_pam_authenticate. You must have PAM authentication configured on the host where you run pamd and you will probably need to run it as root. This is best done using two windows; start pamd in the first window and then telnet to it from the second window.
An interaction to perform username/password authentication
will look something like the following
(substitute your jurisdiction's name for
your jurisdiction's domain name or IP address for
and use a username and password pair that is recognized on your system).
The first telnet connection receives a prompt
for a username
Login:" and assigned the variable name
AUTH_PROMPT_VAR1) from pamd,
a transaction identifier (
10.0.0.124:56372:66664:53983facb39881b2" for this
session, and port number to use for subsequent operations belonging to this
The second telnet connection provides the
TRANSID and username
and receives a prompt for a password
Password:", assigned the variable name
The third telnet connection provides the
TRANSID and the password
and receives the result of authentication ("
# ./pamd -uj myjur -ll debug -daemon -unsecure -nofork pamd[info]: Site config file is "/usr/local/dacs/federations/site.conf" pamd[info]: Config file is "/usr/local/dacs/federations/dacs.conf" pamd[info]: This is jurisdiction DSS::myjur pamd[info]: Secure mode is off pamd[debug]: Waiting for initial input block... pamd[debug]: No username pamd[debug]: Calling pam_authenticate pamd[debug]: pamd_conv: reply to port 62475 pamd[debug]: TRANSID is "10.0.0.124:56372:66664:53983facb39881b2" pamd[debug]: type="text" pamd[debug]: label="Login:" pamd[debug]: varname="AUTH_PROMPT_VAR1" pamd[debug]: pamd_conv: waiting 60 seconds for reply pamd[debug]: pamd_conv: received connection pamd[debug]: Reading reply... pamd[debug]: pamd_conv: reply to port 62475 pamd[debug]: TRANSID is "10.0.0.124:62475:66695:fc855a7d68e8b1eb" pamd[debug]: type="password" pamd[debug]: label="Password:" pamd[debug]: varname="AUTH_PROMPT_VAR2" pamd[debug]: pamd_conv: waiting 60 seconds for reply pamd[debug]: pamd_conv: received connection pamd[debug]: Reading reply... pamd[debug]: Success pamd[debug]: result="ok" pamd[debug]: username="auggie"
% telnet myjur.example.com 17000 Trying 10.0.0.124... Connected to bsd6.dss.bc.ca. Escape character is '^]'. Connection closed by foreign host. % telnet myjur.example.com 62475 Trying 10.0.0.124... Connected to bsd6.dss.bc.ca. Escape character is '^]'. TRANSID="10.0.0.124:62475:66695:fc855a7d68e8b1eb" AUTH_PROMPT_VAR1="auggie" Connection closed by foreign host. % telnet myjur.example.com 62475 Trying 10.0.0.124... Connected to bsd6.dss.bc.ca. Escape character is '^]'. TRANSID="10.0.0.124:62475:66695:fc855a7d68e8b1eb" AUTH_PROMPT_VAR2="doggy" result="ok" username="auggie" Connection closed by foreign host.
-daemon flag should cause the process to
detach and put itself in the background unless overridden by another flag;
at present it must be started in the background "manually".
-http flag, which would allow a
pamd session to be started with a web service
request, is not implemented.
Distributed Systems Software (www.dss.ca)
Copyright © 2003-2021 Distributed Systems Software.
file that accompanies the distribution
for licensing information.
|DACS Version 1.4.46||8-Jun-2021||PAMD(8)|
|Table of Contents||
$Id: pamd.8.xml 3137 2020-05-21 23:00:35Z brachman $